Improving the Performance of 2,9-Didecyldinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene Organic Thin-Film-Transistors Using Cyclothiocarbonate- and Decyloxytriphenyl-Modified Polymethacrylate Insulators

The threshold voltage and mobility of organic thin-film transistors (OTFTs) are influenced not only by the dielectric constant of the insulating layer but also by the crystallinity at the interface between the semiconductor and the insulating layer. The crystallization of 2,9-didecyldinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (C10-DNTT) is driven by molecular fastening effects from its long alkyl chains and π–π* stacking interactions. This work proposes a method utilizing the interaction of interfacial functional groups to create nucleation centers for C10-DNTT, thus reducing grain boundaries. We synthesized the homopolymer poly(4-(1,3-dithia-2thioxocyclopentyl) methacrylate) (P(TCMA)), which possesses side chains with high dipole moment thiocarbonate groups, and the copolymer poly(4-(1,3-dithia-2thioxocyclopentyl) methacrylate-co-10-([1,1’:4′,1″-terphenyl]-3-yloxy) decyl methacrylate) (P(TCMA-co-10TPOMA)), which contains decyloxytriphenyl groups in its side chains. The mobility of OTFT devices increased from 0.84 cm2 V–1 s–1 with cured P(TCMA) as the insulating layer to 2.97 cm2 V–1 s–1 with cured P(TCMA-co-10TPOMA)-5, reaching a maximum of 3.40 cm2 V–1 s–1 when P(TCMA-co-10TPOMA)-15 was used as the insulating layer, making it a promising candidate for direct application in drive units.